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Questions tagged [rf]

Short for Radio-Frequency. Frequencies at which radiation (intentional or not) plays a role. Typically associated with wireless communications, but also relevant for high-speed PCB design.

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RF Development board layout questions

I was looking at the development board layout for the MMZ09312B and I had a few questions: datasheet: http://cache.freescale.com/files/rf_if/doc/data_sheet/MMZ09312B.pdf Are large polygon pours away ...
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RF Antenna design for 2 different operating frequencies

I have noticed that my mobile phone sometimes shows it is using the 3G and then other times the 4G. How is that possible if they are using the same antenna? I assume it would use a microcontroller ...
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1answer
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RF measurement setup

I'm trying to take a simple measurement of ~2.4 GHz (WiFi land) with an RF spectrum analyzer (Tektronix RSA607A) but have so far been unsuccessful. On the RF In ...
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3answers
117 views

bike won't start until rider wear helmet [closed]

I am trying to make a project in which ignition system of bike will not start until the rider would wear a helmet. This can be done through RF Transmitter and receiver, but how it will be achieved? ...
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72 views

Connection between RF output to the source for minimum loss and maximum power transfer

The bottom device in the left image is an RF generator with ratings 230V, 15A (max), 13.56 MHz and variable controllable output power up to 1250 W. The top device is an auto match. The metal strip ...
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46 views

Commercial broadband RF amplifiers

In the process of designing a broadband RF amplifier, I've come across some commercial boards, claiming gain flatnesses of +-1db from DC to 1Ghz. Those boards are ridiculously simple, having only one ...
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11 views

Determing proper wireless parameters for HMTRP radio module

I'm trying to properly setup an HM-TRP FSK radio module to send and receive data the best it can at 56kbps. I think I'm wrong with setting it up to use 600Khz "receive bandwidth" and 160Khz "modulate ...
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19 views

How can i maximize the reception of simple RF on a moving object

I have a simple 2 channel rf mouted on a minikart, how can i maximize the reception when the kart is on track?
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1answer
32 views

Trying to read the data from an ASK RF transmitter

I'm trying to duplicate the operation of a simple RF remote control (for some remote power outlets). In the remote control there is an unmarked 8-pin microcontroller. I've worked out which pins are ...
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2answers
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What is a tone (in context of IMD)?

I've seen the term "tone" used a lot in RF literature, but haven't found any helpful explanation of what exactly a tone is. I am looking at tone in context of IMD; i.e. the fundamental input tones. ...
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RF signal zone detection [closed]

I try to detect presence of any RF(in fact 0-6GHz) transmitter in a closed room. So I have 3 SDR platform(like ettus B210) in the room. Also, I want to estimate RF transmitter zone(region) based on ...
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Question related to two closely separated signals that need to be analyzed by a spectrum analyzer

Question The settings of a spectrum analyzer are given as following: Center Frequency = 1.89 GHz, RBW = 10 kHz, VBW = 10 kHz and Span = 50MHz. The Reference Level is set to -20 dBm and ...
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1answer
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Question related to the interference seen at the spectrum analyzer's receiver

I am preparing for the RF course exam. I have an old question on hand that I am trying to solve. Please review my attempt. Question: A simple spectrum analyzer with superheterodyne receiver ...
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Electro magnetic interference with Arduino Uno and a portable radio

I'm surprised when I'm working with Arduino Uno, by just sitting beside a portable radio, like when I was powered on both Arduino & Radio and when they are close to each other I got some noise ...
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Why are there so many vias on this board?

I was looking at the MMZ09312BT1 development board layout, and I was curious about all the holes they have on the board. Are these vias? What is their purpose (I heard somewhere that they are meant as ...
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1answer
32 views

Receiver Antenna Gain

How is gain defined for a receiver antenna? If we look at a radiating antenna, there is a Pin, and the gain in a particular direction would be the radiation intensity Ur, divided by the radiation ...
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2answers
125 views

Why aren't tethered balloons used instead of Cellphone towers? [closed]

If we use tethered balloons with wireless gateways fitted on them (let's say for Cellular or LPWAN communication), they can provide much more coverage. Why aren't they used then? While there are many ...
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1k views

Difference between these RF adapters

Can someone explain me the differences between these two RF adapters. I know the one on the right is better (and much more expensive as well) but is there a difference in the functioning of these ...
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1answer
17 views

Connected RF Trace to Multiple Pads

I'm trying to improve my RF routing skills. I want to connect a 450 MHz trace (21mil width) to a RF6886TR13 power amplifier that has 6 RF_OUT pins. What is the best way to make this connection? I've ...
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1answer
39 views

How to determine the frequencies in which the L&C model of an artificial transmission line works?

I want to model an artificial transmission line with L & C. So far I used the following circuit and used the values of L=400 pH and C=0.16 pF so that Z=sqrt(L/C)=50 ohms. So, expected S21 and S31 ...
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1answer
29 views

How exactly averaging is performed in the diode sensor based power meter?

I was just wondering how the power averaging works in the diode sensor based power meter. Can you please enlighten me? Thank you.
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1answer
56 views

How to convert Inductor to series transmission line?

My objective is to understand the travelling wave amplifiers, but I am stuck on how to realize inductors in transmission lines. But, I am basically stuck on how to convert a series inductor to a ...
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0answers
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Relationship between RBW and sweep time in time-domain and frequency-domain of a spectrum anaylzer?

In frequency domain of a spectrum analyzer, e.g., from Agilent, if RBW increases, then sweep time decreases. However, my observation in time domain of the spectrum analyzer (i.e., at zero span) is ...
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1answer
43 views

How to design a 180 degree phase inverter for the feedback?

I am currently working on a multi-stage wideband amplifier (80-110 GHz) design with the goal of having 5-6 dB for each stage. The transistor that I am using has the transit frequency around 300 GHz (...
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1answer
192 views

The S parameters of an attenuator--but what is actually wrong with it?

I have measured S parameters of an 10 dB attenuator on hand--please see the attachment. In my view, this attenuator is not performing as expected, e.g., |S12| / |S21| is not giving 10dB attenuation ...
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1answer
31 views

In what way VBW and trace averaging are different in spectrum analyzer?

We know both VBW and trace averaging intends to smooth the fluctuations of a spectrum. But how do they differ from each other?
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1answer
49 views

Impact of “reference level” and “RBW” on the time domain signal in spectrum analyzer?

Two questions: (1) What is the impact of "reference level" on the time-domain signal viewed on the spectrum analyzer? [My attempt] Mean power level of a time domain signal would move up and down on ...
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2answers
45 views

Questions related to the calibration of a VNA?

I am seeking answers to these two questions related to the calibration of the VNA. (1) What type of VNA calibration is required to measure the reflection, transmission, and phase of an attenuator? [...
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1answer
53 views

Converting dBuA to dBuV at 3m and 10m

I'm looking for some advice on converting from dBuA/m to dBuV/m at 10m. I'm trying to convert 10dBuA/m @ 10m. I'm struggling with the uA to uV conversion at distance and can't find online tools to do ...
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0answers
21 views

Zigbee power amplifiers

Zigbee transmitters uses OQPSK combined with half IF pulse shaping which results in a signal having a constant envelop and which does not suffer from linearity issues and thus can be driven close to ...
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1answer
53 views

Matching impedance network for an LC ladder network

Let's say I have a 5 stage L-C ladder network with L= 4.7 micro Henry and C= 60 pF. The characteristic impedance of the network becomes 280 ohms (square root(L/C)). However, from circuit analysis, the ...
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1answer
61 views

RF layout bend over Component

We lay out the RF trace for below model. GSM 900MHz RF trace maintain at 50Ω impedance. As I know, the RF trace needs to be as short as possible for better signal. Do we need to bend RF trace ...
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26 views

2 tone test with RF mixer

I am designing a system that uses RF to probe the nonlinearity of a target. It works as follows. Transmitter sends out 2 RF frequencies, such as 900 and 910MHz. The target/reflector has a ...
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56 views

RF Receiver circuit for RC Car

I want to build a RC car, which I can modify at any time,and I had this PT8A978BPE IC (datasheet:https://www.diodes.com/assets/Datasheets/PT8A977B978B978BL.pdf) lying around from an older teardown of ...
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1answer
54 views

Effects of impedance mismatch on RF signals from antenna

I'm building an antenna array that operates at high frequencies (around 2 GHz). I want to use a SDR dongle that has a 75 ohm input impedance as receiver, I've also bought the coax cable, a 4 way ...
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2answers
98 views

Conversion from dBm to dB\$\mu\$V?

I am trying to derive the conversion from dBm to dB\$\mu\$V. So, please correct me If I am wrong. \begin{align} \textrm{dBm} &= 10 \log_{10} \left( \frac{P}{1\textrm{mW}} \right) = 10 \log(P) + ...
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Queries regarding multiple reflections

I have a measurement set-up as depicted in the figure below. The measurement settings are as following: Both Generator 1 were having carrier frequency 1 GHz and output power 0 dBm. No modulation as ...
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0answers
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How would one perform a gage R&R analysis on a network analyzer?

Was wondering if someone would elaborate on the steps to performing a gage R&R analysis. I understand how one works for something that performs a single measurement, but network analyzers perform ...
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1answer
62 views

Design emission (harmonics)

I attached a image of ESP32's datasheet where it say to add a series 470 ohm resistor to Tx transmission line. I wonder is it talking about which line, what are the pins? And why that specific value? ...
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5answers
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How could have Banksy kept an RF receiver running for 12 years? [closed]

I'm talking about Banksy's "Girl with balloon" painting that shredded itself at auction. I think the general consensus is that he didn't, and that it was set up before the auction (or a couple years ...
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1answer
50 views

Reference Plane In Impedance Calculation

I'm designing an 8-layer PCB with 10 distinct region of power. To attain 50Ohm trace I used Stripline calculators (like this fancy EEWeb) and they work great If you know that you have a complete solid ...
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1answer
40 views

Radio activated on/off switch

TL;DR: I want to know if there is anything, That on which when a radio frequency falls, and it turns on an LED. Basically an on off switch but controlled when radio waves hit it. What I hope to ...
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2answers
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Should the antenna be 'better' for the transmitter or receiver?

I intend for this to be a general/conceptual question that could apply to any wireless communication setup, however I will use a specific example to make things easier. For my example, I'll be ...
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2answers
43 views

Measure ~300kHz Induction Heater RF Power

I have been tasked to gather data from an old running 335kHz 5kW induction heater system. It has no outputs available to give amperage, power etc. Basically there is an assumption that the unit is not ...
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0answers
32 views

Generate ultrashort rise times with photoconductive switch or photodiode

I am trying to produce voltage pulses with very short rise time (<15 ps), medium width (20 ns) and amplitudes up to 15 V. As a promising candidate I selected photoconductive switches and ultrafast ...
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1answer
30 views

Un-masked Copper Boundary across RF section

I have seen so many PCB which has an un-masked (without solder mask), copper boundary across RF sections. The boundary has via-stitching and there are also few ...
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1answer
40 views

When deforming a resonant circuit into an antenna, why can we cut the inductor in half?

The working principle and fields of an antenna can often be shown by considering a parallel LC circuit. The plates can be moved to opposite ends and the inductor can be stretched out, both of which ...
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1answer
29 views

What is the relation between carrier signal and local oscillator in RF system?

I have a confusion between the carrier signal and the local oscillator and based on my understanding, IQ signal (data) is mixed with carrier signal to become a modulated RF signal and before ...
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0answers
40 views

Impedance matching network

Can anyone suggest tools or reading material that discusses how to impedance match for multiple frequency bands (where they are not multiples of one another)? For example, the input impedance of my ...
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0answers
45 views

Trying to find appropriate RF mixer

I am a grad student looking for a downconverting mixer, operating at ~900MHz. I am making a back-reflection data transmitter, similar to RFID. It needs to do the following: Mixer Params: LO_in = ...